linux/block/bsg.c
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   1/*
   2 * bsg.c - block layer implementation of the sg v4 interface
   3 *
   4 * Copyright (C) 2004 Jens Axboe <axboe@suse.de> SUSE Labs
   5 * Copyright (C) 2004 Peter M. Jones <pjones@redhat.com>
   6 *
   7 *  This file is subject to the terms and conditions of the GNU General Public
   8 *  License version 2.  See the file "COPYING" in the main directory of this
   9 *  archive for more details.
  10 *
  11 */
  12#include <linux/module.h>
  13#include <linux/init.h>
  14#include <linux/file.h>
  15#include <linux/blkdev.h>
  16#include <linux/poll.h>
  17#include <linux/cdev.h>
  18#include <linux/percpu.h>
  19#include <linux/uio.h>
  20#include <linux/idr.h>
  21#include <linux/bsg.h>
  22#include <linux/smp_lock.h>
  23
  24#include <scsi/scsi.h>
  25#include <scsi/scsi_ioctl.h>
  26#include <scsi/scsi_cmnd.h>
  27#include <scsi/scsi_device.h>
  28#include <scsi/scsi_driver.h>
  29#include <scsi/sg.h>
  30
  31#define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
  32#define BSG_VERSION     "0.4"
  33
  34struct bsg_device {
  35        struct request_queue *queue;
  36        spinlock_t lock;
  37        struct list_head busy_list;
  38        struct list_head done_list;
  39        struct hlist_node dev_list;
  40        atomic_t ref_count;
  41        int queued_cmds;
  42        int done_cmds;
  43        wait_queue_head_t wq_done;
  44        wait_queue_head_t wq_free;
  45        char name[BUS_ID_SIZE];
  46        int max_queue;
  47        unsigned long flags;
  48};
  49
  50enum {
  51        BSG_F_BLOCK             = 1,
  52};
  53
  54#define BSG_DEFAULT_CMDS        64
  55#define BSG_MAX_DEVS            32768
  56
  57#undef BSG_DEBUG
  58
  59#ifdef BSG_DEBUG
  60#define dprintk(fmt, args...) printk(KERN_ERR "%s: " fmt, __func__, ##args)
  61#else
  62#define dprintk(fmt, args...)
  63#endif
  64
  65static DEFINE_MUTEX(bsg_mutex);
  66static DEFINE_IDR(bsg_minor_idr);
  67
  68#define BSG_LIST_ARRAY_SIZE     8
  69static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
  70
  71static struct class *bsg_class;
  72static int bsg_major;
  73
  74static struct kmem_cache *bsg_cmd_cachep;
  75
  76/*
  77 * our internal command type
  78 */
  79struct bsg_command {
  80        struct bsg_device *bd;
  81        struct list_head list;
  82        struct request *rq;
  83        struct bio *bio;
  84        struct bio *bidi_bio;
  85        int err;
  86        struct sg_io_v4 hdr;
  87        char sense[SCSI_SENSE_BUFFERSIZE];
  88};
  89
  90static void bsg_free_command(struct bsg_command *bc)
  91{
  92        struct bsg_device *bd = bc->bd;
  93        unsigned long flags;
  94
  95        kmem_cache_free(bsg_cmd_cachep, bc);
  96
  97        spin_lock_irqsave(&bd->lock, flags);
  98        bd->queued_cmds--;
  99        spin_unlock_irqrestore(&bd->lock, flags);
 100
 101        wake_up(&bd->wq_free);
 102}
 103
 104static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
 105{
 106        struct bsg_command *bc = ERR_PTR(-EINVAL);
 107
 108        spin_lock_irq(&bd->lock);
 109
 110        if (bd->queued_cmds >= bd->max_queue)
 111                goto out;
 112
 113        bd->queued_cmds++;
 114        spin_unlock_irq(&bd->lock);
 115
 116        bc = kmem_cache_zalloc(bsg_cmd_cachep, GFP_KERNEL);
 117        if (unlikely(!bc)) {
 118                spin_lock_irq(&bd->lock);
 119                bd->queued_cmds--;
 120                bc = ERR_PTR(-ENOMEM);
 121                goto out;
 122        }
 123
 124        bc->bd = bd;
 125        INIT_LIST_HEAD(&bc->list);
 126        dprintk("%s: returning free cmd %p\n", bd->name, bc);
 127        return bc;
 128out:
 129        spin_unlock_irq(&bd->lock);
 130        return bc;
 131}
 132
 133static inline struct hlist_head *bsg_dev_idx_hash(int index)
 134{
 135        return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
 136}
 137
 138static int bsg_io_schedule(struct bsg_device *bd)
 139{
 140        DEFINE_WAIT(wait);
 141        int ret = 0;
 142
 143        spin_lock_irq(&bd->lock);
 144
 145        BUG_ON(bd->done_cmds > bd->queued_cmds);
 146
 147        /*
 148         * -ENOSPC or -ENODATA?  I'm going for -ENODATA, meaning "I have no
 149         * work to do", even though we return -ENOSPC after this same test
 150         * during bsg_write() -- there, it means our buffer can't have more
 151         * bsg_commands added to it, thus has no space left.
 152         */
 153        if (bd->done_cmds == bd->queued_cmds) {
 154                ret = -ENODATA;
 155                goto unlock;
 156        }
 157
 158        if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 159                ret = -EAGAIN;
 160                goto unlock;
 161        }
 162
 163        prepare_to_wait(&bd->wq_done, &wait, TASK_UNINTERRUPTIBLE);
 164        spin_unlock_irq(&bd->lock);
 165        io_schedule();
 166        finish_wait(&bd->wq_done, &wait);
 167
 168        return ret;
 169unlock:
 170        spin_unlock_irq(&bd->lock);
 171        return ret;
 172}
 173
 174static int blk_fill_sgv4_hdr_rq(struct request_queue *q, struct request *rq,
 175                                struct sg_io_v4 *hdr, struct bsg_device *bd,
 176                                fmode_t has_write_perm)
 177{
 178        if (hdr->request_len > BLK_MAX_CDB) {
 179                rq->cmd = kzalloc(hdr->request_len, GFP_KERNEL);
 180                if (!rq->cmd)
 181                        return -ENOMEM;
 182        }
 183
 184        if (copy_from_user(rq->cmd, (void *)(unsigned long)hdr->request,
 185                           hdr->request_len))
 186                return -EFAULT;
 187
 188        if (hdr->subprotocol == BSG_SUB_PROTOCOL_SCSI_CMD) {
 189                if (blk_verify_command(&q->cmd_filter, rq->cmd, has_write_perm))
 190                        return -EPERM;
 191        } else if (!capable(CAP_SYS_RAWIO))
 192                return -EPERM;
 193
 194        /*
 195         * fill in request structure
 196         */
 197        rq->cmd_len = hdr->request_len;
 198        rq->cmd_type = REQ_TYPE_BLOCK_PC;
 199
 200        rq->timeout = (hdr->timeout * HZ) / 1000;
 201        if (!rq->timeout)
 202                rq->timeout = q->sg_timeout;
 203        if (!rq->timeout)
 204                rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
 205        if (rq->timeout < BLK_MIN_SG_TIMEOUT)
 206                rq->timeout = BLK_MIN_SG_TIMEOUT;
 207
 208        return 0;
 209}
 210
 211/*
 212 * Check if sg_io_v4 from user is allowed and valid
 213 */
 214static int
 215bsg_validate_sgv4_hdr(struct request_queue *q, struct sg_io_v4 *hdr, int *rw)
 216{
 217        int ret = 0;
 218
 219        if (hdr->guard != 'Q')
 220                return -EINVAL;
 221        if (hdr->dout_xfer_len > (q->max_sectors << 9) ||
 222            hdr->din_xfer_len > (q->max_sectors << 9))
 223                return -EIO;
 224
 225        switch (hdr->protocol) {
 226        case BSG_PROTOCOL_SCSI:
 227                switch (hdr->subprotocol) {
 228                case BSG_SUB_PROTOCOL_SCSI_CMD:
 229                case BSG_SUB_PROTOCOL_SCSI_TRANSPORT:
 230                        break;
 231                default:
 232                        ret = -EINVAL;
 233                }
 234                break;
 235        default:
 236                ret = -EINVAL;
 237        }
 238
 239        *rw = hdr->dout_xfer_len ? WRITE : READ;
 240        return ret;
 241}
 242
 243/*
 244 * map sg_io_v4 to a request.
 245 */
 246static struct request *
 247bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm)
 248{
 249        struct request_queue *q = bd->queue;
 250        struct request *rq, *next_rq = NULL;
 251        int ret, rw;
 252        unsigned int dxfer_len;
 253        void *dxferp = NULL;
 254
 255        dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
 256                hdr->dout_xfer_len, (unsigned long long) hdr->din_xferp,
 257                hdr->din_xfer_len);
 258
 259        ret = bsg_validate_sgv4_hdr(q, hdr, &rw);
 260        if (ret)
 261                return ERR_PTR(ret);
 262
 263        /*
 264         * map scatter-gather elements seperately and string them to request
 265         */
 266        rq = blk_get_request(q, rw, GFP_KERNEL);
 267        if (!rq)
 268                return ERR_PTR(-ENOMEM);
 269        ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
 270        if (ret)
 271                goto out;
 272
 273        if (rw == WRITE && hdr->din_xfer_len) {
 274                if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
 275                        ret = -EOPNOTSUPP;
 276                        goto out;
 277                }
 278
 279                next_rq = blk_get_request(q, READ, GFP_KERNEL);
 280                if (!next_rq) {
 281                        ret = -ENOMEM;
 282                        goto out;
 283                }
 284                rq->next_rq = next_rq;
 285                next_rq->cmd_type = rq->cmd_type;
 286
 287                dxferp = (void*)(unsigned long)hdr->din_xferp;
 288                ret =  blk_rq_map_user(q, next_rq, NULL, dxferp,
 289                                       hdr->din_xfer_len, GFP_KERNEL);
 290                if (ret)
 291                        goto out;
 292        }
 293
 294        if (hdr->dout_xfer_len) {
 295                dxfer_len = hdr->dout_xfer_len;
 296                dxferp = (void*)(unsigned long)hdr->dout_xferp;
 297        } else if (hdr->din_xfer_len) {
 298                dxfer_len = hdr->din_xfer_len;
 299                dxferp = (void*)(unsigned long)hdr->din_xferp;
 300        } else
 301                dxfer_len = 0;
 302
 303        if (dxfer_len) {
 304                ret = blk_rq_map_user(q, rq, NULL, dxferp, dxfer_len,
 305                                      GFP_KERNEL);
 306                if (ret)
 307                        goto out;
 308        }
 309        return rq;
 310out:
 311        if (rq->cmd != rq->__cmd)
 312                kfree(rq->cmd);
 313        blk_put_request(rq);
 314        if (next_rq) {
 315                blk_rq_unmap_user(next_rq->bio);
 316                blk_put_request(next_rq);
 317        }
 318        return ERR_PTR(ret);
 319}
 320
 321/*
 322 * async completion call-back from the block layer, when scsi/ide/whatever
 323 * calls end_that_request_last() on a request
 324 */
 325static void bsg_rq_end_io(struct request *rq, int uptodate)
 326{
 327        struct bsg_command *bc = rq->end_io_data;
 328        struct bsg_device *bd = bc->bd;
 329        unsigned long flags;
 330
 331        dprintk("%s: finished rq %p bc %p, bio %p stat %d\n",
 332                bd->name, rq, bc, bc->bio, uptodate);
 333
 334        bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);
 335
 336        spin_lock_irqsave(&bd->lock, flags);
 337        list_move_tail(&bc->list, &bd->done_list);
 338        bd->done_cmds++;
 339        spin_unlock_irqrestore(&bd->lock, flags);
 340
 341        wake_up(&bd->wq_done);
 342}
 343
 344/*
 345 * do final setup of a 'bc' and submit the matching 'rq' to the block
 346 * layer for io
 347 */
 348static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,
 349                            struct bsg_command *bc, struct request *rq)
 350{
 351        rq->sense = bc->sense;
 352        rq->sense_len = 0;
 353
 354        /*
 355         * add bc command to busy queue and submit rq for io
 356         */
 357        bc->rq = rq;
 358        bc->bio = rq->bio;
 359        if (rq->next_rq)
 360                bc->bidi_bio = rq->next_rq->bio;
 361        bc->hdr.duration = jiffies;
 362        spin_lock_irq(&bd->lock);
 363        list_add_tail(&bc->list, &bd->busy_list);
 364        spin_unlock_irq(&bd->lock);
 365
 366        dprintk("%s: queueing rq %p, bc %p\n", bd->name, rq, bc);
 367
 368        rq->end_io_data = bc;
 369        blk_execute_rq_nowait(q, NULL, rq, 1, bsg_rq_end_io);
 370}
 371
 372static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)
 373{
 374        struct bsg_command *bc = NULL;
 375
 376        spin_lock_irq(&bd->lock);
 377        if (bd->done_cmds) {
 378                bc = list_first_entry(&bd->done_list, struct bsg_command, list);
 379                list_del(&bc->list);
 380                bd->done_cmds--;
 381        }
 382        spin_unlock_irq(&bd->lock);
 383
 384        return bc;
 385}
 386
 387/*
 388 * Get a finished command from the done list
 389 */
 390static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)
 391{
 392        struct bsg_command *bc;
 393        int ret;
 394
 395        do {
 396                bc = bsg_next_done_cmd(bd);
 397                if (bc)
 398                        break;
 399
 400                if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
 401                        bc = ERR_PTR(-EAGAIN);
 402                        break;
 403                }
 404
 405                ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);
 406                if (ret) {
 407                        bc = ERR_PTR(-ERESTARTSYS);
 408                        break;
 409                }
 410        } while (1);
 411
 412        dprintk("%s: returning done %p\n", bd->name, bc);
 413
 414        return bc;
 415}
 416
 417static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
 418                                    struct bio *bio, struct bio *bidi_bio)
 419{
 420        int ret = 0;
 421
 422        dprintk("rq %p bio %p %u\n", rq, bio, rq->errors);
 423        /*
 424         * fill in all the output members
 425         */
 426        hdr->device_status = status_byte(rq->errors);
 427        hdr->transport_status = host_byte(rq->errors);
 428        hdr->driver_status = driver_byte(rq->errors);
 429        hdr->info = 0;
 430        if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 431                hdr->info |= SG_INFO_CHECK;
 432        hdr->response_len = 0;
 433
 434        if (rq->sense_len && hdr->response) {
 435                int len = min_t(unsigned int, hdr->max_response_len,
 436                                        rq->sense_len);
 437
 438                ret = copy_to_user((void*)(unsigned long)hdr->response,
 439                                   rq->sense, len);
 440                if (!ret)
 441                        hdr->response_len = len;
 442                else
 443                        ret = -EFAULT;
 444        }
 445
 446        if (rq->next_rq) {
 447                hdr->dout_resid = rq->data_len;
 448                hdr->din_resid = rq->next_rq->data_len;
 449                blk_rq_unmap_user(bidi_bio);
 450                blk_put_request(rq->next_rq);
 451        } else if (rq_data_dir(rq) == READ)
 452                hdr->din_resid = rq->data_len;
 453        else
 454                hdr->dout_resid = rq->data_len;
 455
 456        /*
 457         * If the request generated a negative error number, return it
 458         * (providing we aren't already returning an error); if it's
 459         * just a protocol response (i.e. non negative), that gets
 460         * processed above.
 461         */
 462        if (!ret && rq->errors < 0)
 463                ret = rq->errors;
 464
 465        blk_rq_unmap_user(bio);
 466        if (rq->cmd != rq->__cmd)
 467                kfree(rq->cmd);
 468        blk_put_request(rq);
 469
 470        return ret;
 471}
 472
 473static int bsg_complete_all_commands(struct bsg_device *bd)
 474{
 475        struct bsg_command *bc;
 476        int ret, tret;
 477
 478        dprintk("%s: entered\n", bd->name);
 479
 480        /*
 481         * wait for all commands to complete
 482         */
 483        ret = 0;
 484        do {
 485                ret = bsg_io_schedule(bd);
 486                /*
 487                 * look for -ENODATA specifically -- we'll sometimes get
 488                 * -ERESTARTSYS when we've taken a signal, but we can't
 489                 * return until we're done freeing the queue, so ignore
 490                 * it.  The signal will get handled when we're done freeing
 491                 * the bsg_device.
 492                 */
 493        } while (ret != -ENODATA);
 494
 495        /*
 496         * discard done commands
 497         */
 498        ret = 0;
 499        do {
 500                spin_lock_irq(&bd->lock);
 501                if (!bd->queued_cmds) {
 502                        spin_unlock_irq(&bd->lock);
 503                        break;
 504                }
 505                spin_unlock_irq(&bd->lock);
 506
 507                bc = bsg_get_done_cmd(bd);
 508                if (IS_ERR(bc))
 509                        break;
 510
 511                tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 512                                                bc->bidi_bio);
 513                if (!ret)
 514                        ret = tret;
 515
 516                bsg_free_command(bc);
 517        } while (1);
 518
 519        return ret;
 520}
 521
 522static int
 523__bsg_read(char __user *buf, size_t count, struct bsg_device *bd,
 524           const struct iovec *iov, ssize_t *bytes_read)
 525{
 526        struct bsg_command *bc;
 527        int nr_commands, ret;
 528
 529        if (count % sizeof(struct sg_io_v4))
 530                return -EINVAL;
 531
 532        ret = 0;
 533        nr_commands = count / sizeof(struct sg_io_v4);
 534        while (nr_commands) {
 535                bc = bsg_get_done_cmd(bd);
 536                if (IS_ERR(bc)) {
 537                        ret = PTR_ERR(bc);
 538                        break;
 539                }
 540
 541                /*
 542                 * this is the only case where we need to copy data back
 543                 * after completing the request. so do that here,
 544                 * bsg_complete_work() cannot do that for us
 545                 */
 546                ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,
 547                                               bc->bidi_bio);
 548
 549                if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))
 550                        ret = -EFAULT;
 551
 552                bsg_free_command(bc);
 553
 554                if (ret)
 555                        break;
 556
 557                buf += sizeof(struct sg_io_v4);
 558                *bytes_read += sizeof(struct sg_io_v4);
 559                nr_commands--;
 560        }
 561
 562        return ret;
 563}
 564
 565static inline void bsg_set_block(struct bsg_device *bd, struct file *file)
 566{
 567        if (file->f_flags & O_NONBLOCK)
 568                clear_bit(BSG_F_BLOCK, &bd->flags);
 569        else
 570                set_bit(BSG_F_BLOCK, &bd->flags);
 571}
 572
 573/*
 574 * Check if the error is a "real" error that we should return.
 575 */
 576static inline int err_block_err(int ret)
 577{
 578        if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)
 579                return 1;
 580
 581        return 0;
 582}
 583
 584static ssize_t
 585bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 586{
 587        struct bsg_device *bd = file->private_data;
 588        int ret;
 589        ssize_t bytes_read;
 590
 591        dprintk("%s: read %Zd bytes\n", bd->name, count);
 592
 593        bsg_set_block(bd, file);
 594
 595        bytes_read = 0;
 596        ret = __bsg_read(buf, count, bd, NULL, &bytes_read);
 597        *ppos = bytes_read;
 598
 599        if (!bytes_read || (bytes_read && err_block_err(ret)))
 600                bytes_read = ret;
 601
 602        return bytes_read;
 603}
 604
 605static int __bsg_write(struct bsg_device *bd, const char __user *buf,
 606                       size_t count, ssize_t *bytes_written,
 607                       fmode_t has_write_perm)
 608{
 609        struct bsg_command *bc;
 610        struct request *rq;
 611        int ret, nr_commands;
 612
 613        if (count % sizeof(struct sg_io_v4))
 614                return -EINVAL;
 615
 616        nr_commands = count / sizeof(struct sg_io_v4);
 617        rq = NULL;
 618        bc = NULL;
 619        ret = 0;
 620        while (nr_commands) {
 621                struct request_queue *q = bd->queue;
 622
 623                bc = bsg_alloc_command(bd);
 624                if (IS_ERR(bc)) {
 625                        ret = PTR_ERR(bc);
 626                        bc = NULL;
 627                        break;
 628                }
 629
 630                if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {
 631                        ret = -EFAULT;
 632                        break;
 633                }
 634
 635                /*
 636                 * get a request, fill in the blanks, and add to request queue
 637                 */
 638                rq = bsg_map_hdr(bd, &bc->hdr, has_write_perm);
 639                if (IS_ERR(rq)) {
 640                        ret = PTR_ERR(rq);
 641                        rq = NULL;
 642                        break;
 643                }
 644
 645                bsg_add_command(bd, q, bc, rq);
 646                bc = NULL;
 647                rq = NULL;
 648                nr_commands--;
 649                buf += sizeof(struct sg_io_v4);
 650                *bytes_written += sizeof(struct sg_io_v4);
 651        }
 652
 653        if (bc)
 654                bsg_free_command(bc);
 655
 656        return ret;
 657}
 658
 659static ssize_t
 660bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 661{
 662        struct bsg_device *bd = file->private_data;
 663        ssize_t bytes_written;
 664        int ret;
 665
 666        dprintk("%s: write %Zd bytes\n", bd->name, count);
 667
 668        bsg_set_block(bd, file);
 669
 670        bytes_written = 0;
 671        ret = __bsg_write(bd, buf, count, &bytes_written,
 672                          file->f_mode & FMODE_WRITE);
 673
 674        *ppos = bytes_written;
 675
 676        /*
 677         * return bytes written on non-fatal errors
 678         */
 679        if (!bytes_written || (bytes_written && err_block_err(ret)))
 680                bytes_written = ret;
 681
 682        dprintk("%s: returning %Zd\n", bd->name, bytes_written);
 683        return bytes_written;
 684}
 685
 686static struct bsg_device *bsg_alloc_device(void)
 687{
 688        struct bsg_device *bd;
 689
 690        bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
 691        if (unlikely(!bd))
 692                return NULL;
 693
 694        spin_lock_init(&bd->lock);
 695
 696        bd->max_queue = BSG_DEFAULT_CMDS;
 697
 698        INIT_LIST_HEAD(&bd->busy_list);
 699        INIT_LIST_HEAD(&bd->done_list);
 700        INIT_HLIST_NODE(&bd->dev_list);
 701
 702        init_waitqueue_head(&bd->wq_free);
 703        init_waitqueue_head(&bd->wq_done);
 704        return bd;
 705}
 706
 707static void bsg_kref_release_function(struct kref *kref)
 708{
 709        struct bsg_class_device *bcd =
 710                container_of(kref, struct bsg_class_device, ref);
 711        struct device *parent = bcd->parent;
 712
 713        if (bcd->release)
 714                bcd->release(bcd->parent);
 715
 716        put_device(parent);
 717}
 718
 719static int bsg_put_device(struct bsg_device *bd)
 720{
 721        int ret = 0, do_free;
 722        struct request_queue *q = bd->queue;
 723
 724        mutex_lock(&bsg_mutex);
 725
 726        do_free = atomic_dec_and_test(&bd->ref_count);
 727        if (!do_free) {
 728                mutex_unlock(&bsg_mutex);
 729                goto out;
 730        }
 731
 732        hlist_del(&bd->dev_list);
 733        mutex_unlock(&bsg_mutex);
 734
 735        dprintk("%s: tearing down\n", bd->name);
 736
 737        /*
 738         * close can always block
 739         */
 740        set_bit(BSG_F_BLOCK, &bd->flags);
 741
 742        /*
 743         * correct error detection baddies here again. it's the responsibility
 744         * of the app to properly reap commands before close() if it wants
 745         * fool-proof error detection
 746         */
 747        ret = bsg_complete_all_commands(bd);
 748
 749        kfree(bd);
 750out:
 751        kref_put(&q->bsg_dev.ref, bsg_kref_release_function);
 752        if (do_free)
 753                blk_put_queue(q);
 754        return ret;
 755}
 756
 757static struct bsg_device *bsg_add_device(struct inode *inode,
 758                                         struct request_queue *rq,
 759                                         struct file *file)
 760{
 761        struct bsg_device *bd;
 762        int ret;
 763#ifdef BSG_DEBUG
 764        unsigned char buf[32];
 765#endif
 766        ret = blk_get_queue(rq);
 767        if (ret)
 768                return ERR_PTR(-ENXIO);
 769
 770        bd = bsg_alloc_device();
 771        if (!bd) {
 772                blk_put_queue(rq);
 773                return ERR_PTR(-ENOMEM);
 774        }
 775
 776        bd->queue = rq;
 777
 778        bsg_set_block(bd, file);
 779
 780        atomic_set(&bd->ref_count, 1);
 781        mutex_lock(&bsg_mutex);
 782        hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));
 783
 784        strncpy(bd->name, rq->bsg_dev.class_dev->bus_id, sizeof(bd->name) - 1);
 785        dprintk("bound to <%s>, max queue %d\n",
 786                format_dev_t(buf, inode->i_rdev), bd->max_queue);
 787
 788        mutex_unlock(&bsg_mutex);
 789        return bd;
 790}
 791
 792static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q)
 793{
 794        struct bsg_device *bd;
 795        struct hlist_node *entry;
 796
 797        mutex_lock(&bsg_mutex);
 798
 799        hlist_for_each_entry(bd, entry, bsg_dev_idx_hash(minor), dev_list) {
 800                if (bd->queue == q) {
 801                        atomic_inc(&bd->ref_count);
 802                        goto found;
 803                }
 804        }
 805        bd = NULL;
 806found:
 807        mutex_unlock(&bsg_mutex);
 808        return bd;
 809}
 810
 811static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file)
 812{
 813        struct bsg_device *bd;
 814        struct bsg_class_device *bcd;
 815
 816        /*
 817         * find the class device
 818         */
 819        mutex_lock(&bsg_mutex);
 820        bcd = idr_find(&bsg_minor_idr, iminor(inode));
 821        if (bcd)
 822                kref_get(&bcd->ref);
 823        mutex_unlock(&bsg_mutex);
 824
 825        if (!bcd)
 826                return ERR_PTR(-ENODEV);
 827
 828        bd = __bsg_get_device(iminor(inode), bcd->queue);
 829        if (bd)
 830                return bd;
 831
 832        bd = bsg_add_device(inode, bcd->queue, file);
 833        if (IS_ERR(bd))
 834                kref_put(&bcd->ref, bsg_kref_release_function);
 835
 836        return bd;
 837}
 838
 839static int bsg_open(struct inode *inode, struct file *file)
 840{
 841        struct bsg_device *bd;
 842
 843        lock_kernel();
 844        bd = bsg_get_device(inode, file);
 845        unlock_kernel();
 846
 847        if (IS_ERR(bd))
 848                return PTR_ERR(bd);
 849
 850        file->private_data = bd;
 851        return 0;
 852}
 853
 854static int bsg_release(struct inode *inode, struct file *file)
 855{
 856        struct bsg_device *bd = file->private_data;
 857
 858        file->private_data = NULL;
 859        return bsg_put_device(bd);
 860}
 861
 862static unsigned int bsg_poll(struct file *file, poll_table *wait)
 863{
 864        struct bsg_device *bd = file->private_data;
 865        unsigned int mask = 0;
 866
 867        poll_wait(file, &bd->wq_done, wait);
 868        poll_wait(file, &bd->wq_free, wait);
 869
 870        spin_lock_irq(&bd->lock);
 871        if (!list_empty(&bd->done_list))
 872                mask |= POLLIN | POLLRDNORM;
 873        if (bd->queued_cmds >= bd->max_queue)
 874                mask |= POLLOUT;
 875        spin_unlock_irq(&bd->lock);
 876
 877        return mask;
 878}
 879
 880static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 881{
 882        struct bsg_device *bd = file->private_data;
 883        int __user *uarg = (int __user *) arg;
 884        int ret;
 885
 886        switch (cmd) {
 887                /*
 888                 * our own ioctls
 889                 */
 890        case SG_GET_COMMAND_Q:
 891                return put_user(bd->max_queue, uarg);
 892        case SG_SET_COMMAND_Q: {
 893                int queue;
 894
 895                if (get_user(queue, uarg))
 896                        return -EFAULT;
 897                if (queue < 1)
 898                        return -EINVAL;
 899
 900                spin_lock_irq(&bd->lock);
 901                bd->max_queue = queue;
 902                spin_unlock_irq(&bd->lock);
 903                return 0;
 904        }
 905
 906        /*
 907         * SCSI/sg ioctls
 908         */
 909        case SG_GET_VERSION_NUM:
 910        case SCSI_IOCTL_GET_IDLUN:
 911        case SCSI_IOCTL_GET_BUS_NUMBER:
 912        case SG_SET_TIMEOUT:
 913        case SG_GET_TIMEOUT:
 914        case SG_GET_RESERVED_SIZE:
 915        case SG_SET_RESERVED_SIZE:
 916        case SG_EMULATED_HOST:
 917        case SCSI_IOCTL_SEND_COMMAND: {
 918                void __user *uarg = (void __user *) arg;
 919                return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg);
 920        }
 921        case SG_IO: {
 922                struct request *rq;
 923                struct bio *bio, *bidi_bio = NULL;
 924                struct sg_io_v4 hdr;
 925
 926                if (copy_from_user(&hdr, uarg, sizeof(hdr)))
 927                        return -EFAULT;
 928
 929                rq = bsg_map_hdr(bd, &hdr, file->f_mode & FMODE_WRITE);
 930                if (IS_ERR(rq))
 931                        return PTR_ERR(rq);
 932
 933                bio = rq->bio;
 934                if (rq->next_rq)
 935                        bidi_bio = rq->next_rq->bio;
 936                blk_execute_rq(bd->queue, NULL, rq, 0);
 937                ret = blk_complete_sgv4_hdr_rq(rq, &hdr, bio, bidi_bio);
 938
 939                if (copy_to_user(uarg, &hdr, sizeof(hdr)))
 940                        return -EFAULT;
 941
 942                return ret;
 943        }
 944        /*
 945         * block device ioctls
 946         */
 947        default:
 948#if 0
 949                return ioctl_by_bdev(bd->bdev, cmd, arg);
 950#else
 951                return -ENOTTY;
 952#endif
 953        }
 954}
 955
 956static const struct file_operations bsg_fops = {
 957        .read           =       bsg_read,
 958        .write          =       bsg_write,
 959        .poll           =       bsg_poll,
 960        .open           =       bsg_open,
 961        .release        =       bsg_release,
 962        .unlocked_ioctl =       bsg_ioctl,
 963        .owner          =       THIS_MODULE,
 964};
 965
 966void bsg_unregister_queue(struct request_queue *q)
 967{
 968        struct bsg_class_device *bcd = &q->bsg_dev;
 969
 970        if (!bcd->class_dev)
 971                return;
 972
 973        mutex_lock(&bsg_mutex);
 974        idr_remove(&bsg_minor_idr, bcd->minor);
 975        sysfs_remove_link(&q->kobj, "bsg");
 976        device_unregister(bcd->class_dev);
 977        bcd->class_dev = NULL;
 978        kref_put(&bcd->ref, bsg_kref_release_function);
 979        mutex_unlock(&bsg_mutex);
 980}
 981EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 982
 983int bsg_register_queue(struct request_queue *q, struct device *parent,
 984                       const char *name, void (*release)(struct device *))
 985{
 986        struct bsg_class_device *bcd;
 987        dev_t dev;
 988        int ret, minor;
 989        struct device *class_dev = NULL;
 990        const char *devname;
 991
 992        if (name)
 993                devname = name;
 994        else
 995                devname = parent->bus_id;
 996
 997        /*
 998         * we need a proper transport to send commands, not a stacked device
 999         */
1000        if (!q->request_fn)
1001                return 0;
1002
1003        bcd = &q->bsg_dev;
1004        memset(bcd, 0, sizeof(*bcd));
1005
1006        mutex_lock(&bsg_mutex);
1007
1008        ret = idr_pre_get(&bsg_minor_idr, GFP_KERNEL);
1009        if (!ret) {
1010                ret = -ENOMEM;
1011                goto unlock;
1012        }
1013
1014        ret = idr_get_new(&bsg_minor_idr, bcd, &minor);
1015        if (ret < 0)
1016                goto unlock;
1017
1018        if (minor >= BSG_MAX_DEVS) {
1019                printk(KERN_ERR "bsg: too many bsg devices\n");
1020                ret = -EINVAL;
1021                goto remove_idr;
1022        }
1023
1024        bcd->minor = minor;
1025        bcd->queue = q;
1026        bcd->parent = get_device(parent);
1027        bcd->release = release;
1028        kref_init(&bcd->ref);
1029        dev = MKDEV(bsg_major, bcd->minor);
1030        class_dev = device_create(bsg_class, parent, dev, NULL, "%s", devname);
1031        if (IS_ERR(class_dev)) {
1032                ret = PTR_ERR(class_dev);
1033                goto put_dev;
1034        }
1035        bcd->class_dev = class_dev;
1036
1037        if (q->kobj.sd) {
1038                ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg");
1039                if (ret)
1040                        goto unregister_class_dev;
1041        }
1042
1043        mutex_unlock(&bsg_mutex);
1044        return 0;
1045
1046unregister_class_dev:
1047        device_unregister(class_dev);
1048put_dev:
1049        put_device(parent);
1050remove_idr:
1051        idr_remove(&bsg_minor_idr, minor);
1052unlock:
1053        mutex_unlock(&bsg_mutex);
1054        return ret;
1055}
1056EXPORT_SYMBOL_GPL(bsg_register_queue);
1057
1058static struct cdev bsg_cdev;
1059
1060static int __init bsg_init(void)
1061{
1062        int ret, i;
1063        dev_t devid;
1064
1065        bsg_cmd_cachep = kmem_cache_create("bsg_cmd",
1066                                sizeof(struct bsg_command), 0, 0, NULL);
1067        if (!bsg_cmd_cachep) {
1068                printk(KERN_ERR "bsg: failed creating slab cache\n");
1069                return -ENOMEM;
1070        }
1071
1072        for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)
1073                INIT_HLIST_HEAD(&bsg_device_list[i]);
1074
1075        bsg_class = class_create(THIS_MODULE, "bsg");
1076        if (IS_ERR(bsg_class)) {
1077                ret = PTR_ERR(bsg_class);
1078                goto destroy_kmemcache;
1079        }
1080
1081        ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");
1082        if (ret)
1083                goto destroy_bsg_class;
1084
1085        bsg_major = MAJOR(devid);
1086
1087        cdev_init(&bsg_cdev, &bsg_fops);
1088        ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1089        if (ret)
1090                goto unregister_chrdev;
1091
1092        printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION
1093               " loaded (major %d)\n", bsg_major);
1094        return 0;
1095unregister_chrdev:
1096        unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);
1097destroy_bsg_class:
1098        class_destroy(bsg_class);
1099destroy_kmemcache:
1100        kmem_cache_destroy(bsg_cmd_cachep);
1101        return ret;
1102}
1103
1104MODULE_AUTHOR("Jens Axboe");
1105MODULE_DESCRIPTION(BSG_DESCRIPTION);
1106MODULE_LICENSE("GPL");
1107
1108device_initcall(bsg_init);
1109